The general change which is taking place in life habits, the greater availability of free time, the possibility to move from one place to another have opened new important markets to products which are able to meet particular requirements. For example in the field of camping and picnic, there is an increasing tendency to adopt specialized outfits suitable for the storage, transport, preparation and consumption of food and drinks. Such new products remarkably differ from those used for the same purposes in normal houses, owing to the specific characteristics which are required from them; they must for example be unbreakable, light in weight, resistent, easy to wash and have a reduced bulkiness and a reduced price; in addition they must possess a new and different aesthetic appearance, brighter and more expressive as to shape and colours.
The arrival of new technologies and materials such as for example synthetic resins has allowed the industrial development of these productions, while modern distribution systems have helped their diffusion all over the different countries.
The field which absorbs a great deal of the production of the above mentioned market is formed by all things needed for a good running of a refectory, namely: plates and soup plates, vessels, cups, fruit and vegetables plates, trays, glasses and different accessories connected thereto.
Taking into account their field of utilization, the most important quality which is required to said articles is to be unbreakable, but it is also important for them to be hygienical, suitable to be superimposed in order to reduce their vertical bulkiness and aid their shifting, washable in water at a rather high temperature, considerably light in weight though sufficiently strong, as well as to have an agreeable aesthetic appearance if possible enriched with decorations.
Obviously said articles are not only used in the field of the free time but they are also used as children kitchenware, promotional articles and decorative articles of normal use in houses, snack-bars, restaurants, etc.
For what concerns the products actually on the market which are obtained by means of different materials and techniques and are therefore divided into different classes, we are going hereinafter to take into account and illustrate those products only which are of a durable kind and can be re-utilized; therefore no mention will be made either to tempered glass and metal productions, which on the other hand are not very suitable for the above stated purposes owing to their weight and to the noise they produce during the transferring, or to kitchenware of the traditional kind, that is chinaware, earthenware, etc.
The most diffused kitchenware is till now the one made of thermosetting resins (such as melamine and urea resins) notwithstanding its very high price. The technique for the production and decoration of this kind of kitchenware contemplates the following steps:
1st step: previous preparation of the decorated insert by means of offset lithography printing of the subject on covering paper made of pure cellulose, that is to say of a composition approaching the material used for the production of the piece.
2nd step: subsequent impregnation of the sheet with liquid malamine resin.
3rd step: dinking of the decorative insert.
4th step: molding of the piece, by heat compression of the resin in a suitable mold up to a value equal to about 50% of the total baking.
5th step: re-opening of the mold.
6th step: introduction of the decorative piece in the mold.
7th step: re-shutting of the mold and consequent completion of the molding step.
During the latter step the paper support of the decorative piece is literally dissolved in the piece which is going to be molded while the ornamental figure resisting to high temperatures owing to the thermoresistent qualities of printing inks used, is kept incorporated in an indelible and permanent manner onto the piece surface.
A further optional though useful operation provides the vitrification of the molded piece obtained by means of a further opening of the mold and consequent introduction of a small quantity of transparent melamine resin, that is free from cellulose, therein, which evenly distributes all over the surface of the piece to be molded when the mold is shut again.
The finished piece will then need a final snagging and finishing operation, owing to the presence of surplus material all around its external edge.
The main drawback of this procedure is represented by the laboriousness of operations necessary for its completion. Owing to the above reasons these articles have an anti-economic cost price (also due to some percent amount of waste pieces which can no more be salvaged) and, in addition, the production cannot meet the demand in due time. On the purpose, it is sufficient to keep in mind that about three minutes are necessary to complete a single molding cycle and therefore, even if more pieces are molded at the same time, the above procedure results almost of the manual art kind. Furthermore, in the pratical use these articles show a reduced abrasion and notch resistance above all where food is placed. Therefore the initial brightness of said surface and consequently of the decorated design is fading little by little, which inevitably reduces the use of a piece that, as to its other features, still appears as new.
Other kinds of kitchenware which are at present on the market are obtained by injection molding of thermoplastic resins (polystyrene, S.A.N., polypropylene, polyamides and so on). This kind of kitchenware is very common in an even colour being rather easy, quick and cheap to be produced; however there are on the market decorated articles too. There exist various procedures and techniques suitable for their production and decoration and for this reason only the most used ones will be hereinafter disclosed.
A first method contemplates a screen-printing process in one or more colours, directly on the molded piece. Inks used for the printing being however very thick, they give rise to some relief on the surface where food has to be placed, which is not very agreeable to the touch and which in addition suggests the idea that these materials are unsuited for getting into contact with food; of course these suspicions are very difficult to verify but are not probably ground-less.
A second method contamplates the possibility of placing an insert into the mold, before the molding of the piece, this insert being previously printed on a film of the same thermoplastic resin using the ordinary graphic techniques. This method, widely used in the past, is no more used at present owing to the poor resistance of the decorated surface which inevitably tends, by use, to exfoliate from the supporting surface.
A third method contemplates a screen-printing in one or more colours directly on the underneath surface of the transparent molded piece and therefore not in contact with food. However this method too does not meet the favour of the consumers because the pieces which are obtained can only be completely transparent and not in a full colour as universally preferred.
A last method contemplates the vacuum forming and subsequent shearing of a continuous thermoplastic material sheet formed by the matching of a support in an even colour with a transparent rotogravure printed film having an endless decorative design, the ink being turned toward the inner surface of the film, in order to avoid its contact with food. Each piece obtained by this process demands a manual finishing; furthermore the only kind existing on the market appears with wood imitating decorations and has to be used for vessels which do not need to be washed in hot water owing to its weak heat resistance. Finally a vessel obtained by this process is rather expensive and encounters many difficulties as to the possibility of varying its decorative designs. Therefore, the limits of the molded pieces obtained by the above processes, as to the aesthetic decoration, colouring and shape possibilities of same, can be synthetized as hereinbefore stated.
For what concerns the pieces obtained with thermosetting resins, the latter allow patterns either in even or in shaded colours (compatibly with the offset lithography printing) however, only when the piece ground is white or has a very light colour. It is not usually possible, for instance, to put white decorations on red grounds. It should also be noted that this kind of decoration is only possible on flat supporting surfaces or at the utmost on supporting surfaces having a weak bending radius. As an exception to these rules we may mention pieces having a peculiar shape, decorative inserts on heavier supports without any possibility of bending, and more complex workings; however the price of each finished piece in this case is even higher.
As to pieces obtained from screen-printed thermoplastic materials, decorations can be carried out in even colours only.
Lastly, as to pieces obtained by means of decorations previously printed on suitable inserts or thermoplastic films (either by injection molding or in vacuum), the same aesthetic limits as with thermosetting resins occur.